The effect of multi-vacancies on the electronic structure of semiconducting C nanotubes was studied using the ab initio pseudopotential density-functional method. The divacancy was found particularly effective in changing the band gap of the semiconducting nanotubes, while mono-, tri-, or tetra-vacancies introduce gap-states. A significant modulation of band gap was observed for a certain type of zig-zag nanotube upon varying concentration of divacancy. The H passivation was found to be critical for stabilizing the vacancies. Based on present calculations, a conceptual model was proposed for semiconductor–semiconductor junctions that did not involve the chirality change of the tube.

An Ab Initio Study of the Electronic Properties of Carbon Nanotubes Activated by Hydrogen-Passivated Vacancies. S.H.Jhi: Carbon, 2007, 45[10], 2031-6